WASHINGTON — US President Donald Trump headed toward Hà Nội on Monday for his second high-stakes summit with the DPRK, with the world watching to see if the US leader can deliver concrete results on curbing the nuclear ambition from Pyongyang.

Tweeting from Air Force One, Trump said he was "looking forward to a very productive Summit," after earlier reiterating his case for North Korean disarmament.

"With complete Denuclearisation, North Korea will rapidly become an Economic Powerhouse," he tweeted. "Without it, just more of the same."

"Chairman Kim will make a wise decision!"

The Hanoi summit comes after Trump and Kim met in June in Singapore, producing a vaguely worded agreement on denuclearisation, but progress has since stalled, with the two sides disagreeing over what the agreement meant.

The summit set for Wednesday and Thursday will present them with a second shot at progress on the world stage.

Trump’s departure after noon on Monday (local time) came as an armored train carrying Kim and members of his delegation arrived in Hà Nội early Tuesday morning. 

United Nations Secretary-General Antonio Guterres said he looked forward to the pair reaching key agreements.

"I hope that the leaders... agree to concrete steps for sustainable, peaceful and complete and verified denuclearisation of the Korean peninsula," Guterres said in a speech in Geneva.

‘Strong deal’ sought

Members of Trump’s Republican Party, however, were demanding the president stand tough, with Senator Marco Rubio calling for the US and its allies to "maximise" pressure on Pyongyang, including immediate intensification of sanctions, if there is no breakthrough.

"American negotiators must push for no less than a strong deal to completely, verifiably, and irreversibly dismantle the North Korean nuclear and missile programmes," Rubio said in a statement minutes after Trump took off.

Pyongyang insists it has already taken appropriate steps by not testing ballistic missiles or nuclear weapons for more than a year and blowing up the entrances to its atomic test site.

But at the same time, the DPRK says it has completed the development of its arsenal and the facilities are no longer needed.

While Pyongyang and Washington have taken guarded approaches to the summit, hopes rose in Seoul that Trump and Kim could formally declare an end to the 1950-53 Korean War, after South Korea said the two leaders could reach an agreement.

The devastating conflict between the DPRK, backed by China, and the South, aided by the United States, ended with an armistice rather than a peace treaty, leaving Pyongyang and Washington still technically at war.

"I believe that the possibility is there," the South’s presidential Blue House spokesman Kim Eui-kyeom told reporters about a formal declaration.

"There is no way of knowing what kind of declaration it might be, but I believe the US and North Korea may reach an agreement."

Trump is expected to arrive in the Vietnamese capital on Tuesday evening local time. — AFP